Field of Invention
A steady activity is defined by statistical characteristics of the activity that do not vary translationally in time, such as the moments of order k, and more particularly the moments of order 1 (for example an average) and the moments of order 2 (for example a correlation).
Examples of steady activities that can be cited include, without being exhaustive, the following activities: racing, swimming, horse riding, body building, etc. These activities in fact exhibit steady phases during which the statistical characteristics remain unchanging in time. They can, however, be interspersed with so-called transient phases during which the animated being changes its activity.
The transient phase corresponds to a state during which the steady activity of the animated being is disrupted, and during which there is a change of the statistical properties. A transient phase can occur in different forms, for example in the form of an obstacle to be overcome (hurdles to be jumped in a sprint or obstacles to be jumped in a horse riding session), a change of direction or of heading of the animated being (change of direction in a series of lengths executed by a swimmer or a racer), or a brief change of activity envisaged by the animated being to interrupt its steady activity (series of bends/extensions when jogging). It is thus possible to find different transient phases in one and the same steady activity. Take, for example, a jogging session in straight lines interrupted by bends/extensions and marked by changes of direction at the end of each straight line. There is an interest in being able to provide the player of the activity with information on this activity, automatically and objectively, by detecting and by counting the number of occurrences of events in the activity. Thus, the detection and counting of the transient phases in an activity may constitute relevant information for the player of the activity.
Description of Related Art
The American patent application U.S. Pat. No. 4,932,045 relates to a system which counts lengths, but with manual intervention on the part of the swimmer. The counter, fixed to the hand or the foot of the swimmer, has to be pressed against the wall of the swimming pool on each turn of the swimmer in order to be incremented by one unit. This device can disrupt the swimming of the athlete.
The American patent application US 2007/0293374 A1 discloses a system that makes it possible to automatically count the lengths of a swimmer without the manual intervention thereof. The go/return counter comprises a box, means for fixing the box to the swimmer, a compass sensor internal to the box to provide an output signal which changes at the time of the turn of the swimmer (i.e. as a function of the go or return direction of the swimmer in the swimming pool) and a processor programmed to detect, in the output signal from the sensor, the change of direction of the swimmer and count the number of go and return lengths of the swimmer.
Such a system includes a certain number of turn detection errors.